The Cancer Epidemiology and Prevention Research Center supports a broad program of studies investigating the etiology of the major human cancers, with the ultimate objective of developing knowledge which will lead to the prevention of these diseases. Focus in research includes: cancer of the breast, especially in relation to patterns of metabolism of endogenous estrogens in young adult life, oral contraceptive use, and other hormonal factors. Hodgkin's disease is another major component of the program with interest in the roles of environmental exposure and person-to-person transmission. Other studies include cancer of the pancreas, multiple myeloma, bladder cancer, and methodoly, including life table analysis of survival data and various aspects of significance testing and interval estimation. Using a variety of resources, the studies employ different epidemiologic approaches including case-control studies, prospective cohort studies, and review of existing data in the Department. Many of these studies are developed on the basis of studies designed and completed in earlier grant years; some studies are supported for a planning phase only; others are continuations of ongoing data collection analysis.